Rename shift_bb() to shift()

[stockfish] / src / timeman.cpp

diff --git a/src/timeman.cpp b/src/timeman.cpp
index e9f1ffe5389597fa52e58fc9fdf604c49ee0af85..6d3b7314705f1098273837863d1dedaf4b94a1bd 100644 (file)
--- a/src/timeman.cpp
+++ b/src/timeman.cpp
@@ -33,29 +33,31 @@ namespace {
   enum TimeType { OptimumTime, MaxTime };
 
   const int MoveHorizon   = 50;   // Plan time management at most this many moves ahead
-  const double MaxRatio   = 7.09;  // When in trouble, we can step over reserved time with this ratio
+  const double MaxRatio   = 7.09; // When in trouble, we can step over reserved time with this ratio
   const double StealRatio = 0.35; // However we must not steal time from remaining moves over this ratio
 
 
-  // move_importance() is an exponential function based on naive observation
-  // that a game is closer to be decided after each half-move. This function
-  // should be decreasing and with "nice" convexity properties.
+  // move_importance() is a skew-logistic function based on naive statistical
+  // analysis of "how many games are still undecided after n half-moves". Game
+  // is considered "undecided" as long as neither side has >275cp advantage.
+  // Data was extracted from the CCRL game database with some simple filtering criteria.
 
   double move_importance(int ply) {
 
-    const double PlyScale = 109.3265;
-    const double PlyGrowth = 4.0;
+    const double XScale = 7.64;
+    const double XShift = 58.4;
+    const double Skew   = 0.183;
 
-    return exp(-pow(ply / PlyScale, PlyGrowth)) + DBL_MIN; // Ensure non-zero
+    return pow((1 + exp((ply - XShift) / XScale)), -Skew) + DBL_MIN; // Ensure non-zero
   }
 
   template<TimeType T>
-  int remaining(int myTime, int movesToGo, int ply)
-  {
+  int remaining(int myTime, int movesToGo, int ply, int slowMover) {
+
     const double TMaxRatio   = (T == OptimumTime ? 1 : MaxRatio);
     const double TStealRatio = (T == OptimumTime ? 0 : StealRatio);
 
-    double moveImportance = move_importance(ply);
+    double moveImportance = (move_importance(ply) * slowMover) / 100;
     double otherMovesImportance = 0;
 
     for (int i = 1; i < movesToGo; ++i)
@@ -79,10 +81,11 @@ namespace {
 ///  inc >  0 && movestogo == 0 means: x basetime + z increment
 ///  inc >  0 && movestogo != 0 means: x moves in y minutes + z increment
 
-void TimeManagement::init(Search::LimitsType& limits, Color us, int ply)
-{
+void TimeManagement::init(Search::LimitsType& limits, Color us, int ply) {
+
   int minThinkingTime = Options["Minimum Thinking Time"];
   int moveOverhead    = Options["Move Overhead"];
+  int slowMover       = Options["Slow Mover"];
   int npmsec          = Options["nodestime"];
 
   // If we have to play in 'nodes as time' mode, then convert from time
@@ -117,8 +120,8 @@ void TimeManagement::init(Search::LimitsType& limits, Color us, int ply)
 
       hypMyTime = std::max(hypMyTime, 0);
 
-      int t1 = minThinkingTime + remaining<OptimumTime>(hypMyTime, hypMTG, ply);
-      int t2 = minThinkingTime + remaining<MaxTime    >(hypMyTime, hypMTG, ply);
+      int t1 = minThinkingTime + remaining<OptimumTime>(hypMyTime, hypMTG, ply, slowMover);
+      int t2 = minThinkingTime + remaining<MaxTime    >(hypMyTime, hypMTG, ply, slowMover);
 
       optimumTime = std::min(t1, optimumTime);
       maximumTime = std::min(t2, maximumTime);